bright



April 11'. 1939. E. M. BREGHT PROCESS OF AND APPARATU$ FOR APPLYING NITROCELLULOSE COATING Original Fild July 23, 19:56

ELVIN BRGHT H IS ATTORNEY.

This invention relates to a process of applyinganitrocelhilosecoatingtoanarticlesndmore particularly to a process of'applying a nitrocellulose coating to an article by dipping.

An object of this invention is to apply a nitrocellulosecoatingtoabodybydipninsthebody in a solution of cellulose material and subsequently controlling the curing of the coating.

Another object of this invention is to treat 0 the nitrocellulose coating applied to the body in the presence of the fumes formed from the sol- Eut used in disolving the nitrocellulose mate- Anotheroblect of this invention is to control the osmotic presure gradient of the solvent within the nitrocellulou coating during the curing thereof.

Another object of this invention is to use a solution for treating the article that has been coated. which solution has an attraction for the solvflent used in dissolving the nitrocellulose mate- Another object of this-invention is to rapidly withdraw the solvent from the nitrocellulose coating near the outer surface for a short period of time, followed by a confinement of the remaining solvent within the nitrocellulose coating for a longer period of time.

Another object of this invention is to periodically withdraw the solvent from near the outer surface of-the coating, followed by alternate periodic confinement of the solvent so as to cause a uniform distribution of the solvent within the Another object of this invention is to apply a a spray of a solution to the article, which solution has an amnity for the solvent used.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will become more apparent from the following description.

Fig. l is a perspective view of a device for ouring the nitrocellulose coating. with parts broken away.

Pig. 2 is a vertical transverse sectional view.

Fig.8isanenlargedfragmentaryviewofthe holder for the article.

Fig. 4 is an enlarged fragmentary view of the article to be finished.

Gases or fumu from a solution consisting of sixty percent acetone, twenty-five percent iso- D 'OPYI acetate and fifteen percent anhydrous isopropanol, sold under the trade name Isotone, have a great afiinity for fumes of certain solutions, such coating during the period that the solvent is con-- "UNITED STATES PATENT OFFICE MSOFANDAPPARATUS FOB APILI-- ING NITBOCELLULOSE COATING llvinll'nrightnaytmohimssdgnortolohn 1!. Wallace, Cincinnati, Ohio, trustee o lthn'l No. 2.130.225, dated September 18, 1988.

Serial No. 92,156, Ji y 23, 1936. for reisue lannary'fl), 1939. Serhi No.

1s (c1. ill-'68) as petroleum distillate, benflne, etc. Fumes of petroleum distlllates maybe obtained by sprayingoperations.

In the past, numerous attempts have been made-to coat bodies with nitrocellulose material. 5

Some have attempted to use solvents which will permit the body to be coated without blisters, pin holes and wrinkling taking place; but the results have been unsatisfactory. The only proc- 'essthathasbeen'usedinthepastthatseemsto 10 be satisfactory is the reduction of the temperature of the coating immediately upon being applied so as to congeal the coatingand thereby deleterious effect upon the outer surface.

This has been accomplished by subjecting the 25 coated article to a solution having a great attraction for the solvent. which solution rapidly withdraws the solvent from the coating. However, if the article is submerged in the sohitlon for a long period of time the attraction of the solution for the solventis sumciently great to create a vacuum in the coating resulting in rapid evaporation, or possibly boiling of the solvent, caming the escaping fumes to form into bubbles, which bubbles probably grow as they move outwardly, resulting in the bubbles leaving voids in the path of travel, which voids form what is generally called pin holes in the surface of the coating.

Before going into details as to the process used, 40 a brief discussion will be made of some of the attributes ,of solvents and of solutes. Whenever the solvent is not evenly distributed throughout the solute, pressures are created within the substances which are generally designated as os- 66 motic pressures. Whenever the osmotic pressure throughout the substances is not uniform, the

, rate of incrase with distance ofthe osmotic pressure within the solvent may be referred to as osmotic pressure gradient. v to If the solvent is volatile it may leave the solute as a vapor. Consequently, when the volatile solventisuseditwillbegintovaporiae, therateof vaporization being influenced among other things by the vapor pressure of the surrounding mediis If the surrounding medium consists of or entisnottobeiniluencedbytheaccuracyofthe includes saturated vapor like that given oil by the solvent, it is reasonable to assume vaporization of the solvent will cease whenever the sur- 5 roundingvaporisthussaturated. 4.

. Insteadoithesolventintoagasemls medium surrounding the article, the solvent may flow possibly as should into a solution having an attraction for the solvent,-ln which solution 10 the soluteoi the coating material is insoluble. Whenthesolventis leavingthesolutein passing into the solution, it probably leaves due to difference in osmotic pressure found within the coating and the solution. If the solvent and its 15 solute is kept in this solution that has a great .attraction for the solvent, the osmotic pressure may possibly be reduced to a point where vaporization takesplace within the solute. As the solvent is withdrawn, it creates a partial vacao uum unless thecoatinglspermitted toset suf-' the nitrocellulose solution were rotated or moved into a solution having a great-attraction for the solventusedinthenitrocellulose material. Gasoline and various other petroleumproducts have ibeenfoundtobeverysatisfactory. Methanol mayalsobeused. Thehallswereremovedwithinashortperlodofflmei'romthegasolineand' suspended in a-medium saturated, or'nearly saturatedwlthfumesfromthesolvent. Theballs 'werethenmomentarilytoairha' overylittlefumes.

Thiswasfollowedhytheballsbeingadvanced intoamedimncontainingagreatamountof fumes and then returned to the solution having a great attraction for the solvent and the cycle repeated. Theseseriesofstepswerecan'ledon cyclicallyforanhouripanhourandilitem minutes, the total time'ior each cycle constitutingtelytwominutes.

I 'romthisltmay'bereadilyseenthatsome thirtytofortycyclesweresuiilcienttocurethe nitrocellulose coating to such an extent that the ballsmightthenberemovedtotheopenairand permittedtodrywithoutpinholesformlnginthe a surface thereof, without blistering and without wrinkling. The resulting surface was found to be smooth. By regulating the viscosity of the nit'rocdlulose solution, the thickness of the coating may be oontrolled'from a few thousandths oflaninchin thicknesato several hundredths of an inch in. th ckness.

Althwghthetheoryoftheproces'shasnotbeen thoroughly the followlm explanation is oil'ered as a plausible theory, with underthat'the scope andsvalidity-of the pat hours after bdng dipped following explanation.

The nitrocellulose material applied to the surfaoeofthearticletobecoateduponbeingplaced in thesolution thathas. an attraction for the solvent used in dissolving the nitrocellulose ma- I terial, gives up some of the solvent. It ls possible that the solvent flows from the nitrocellulose coating where it is insoluble in the solution having an attraction for the solvent under the influence of osmotic pressure. That is, the solvent drains from the nitrocellulose coating into the solution.

If. however, this operation is continued for a long period of time, the motic pressure gradient becomes suliliciently steep or great from the outddetotheinsideofthecoatingsoastocause the solvent to evaporate very rapidly and possibly This rapid evaporation or boiling, which ever it may be, if it is not checked, will cause bubbles to form within the nitrocellulow coating, which bubbles are attracted to the outer coating of the nitrocellulose wherethey burst, leaving voids surrounded by a dimple, generally referred to as pin holes.

Therefore, it is to check the rapid giving oil of the solvent, as it is very desirable to have the surface of the finished product smooth and uniform, without any deformities or irregularities in the surface. In the past, attempts have been made to douse the coated artlcle into cold gasoline and then remove it into the open atmosphere: but the vapor pressure in the open atmosphere is suiiiciently low to permit thesolvent'toescapeintotheairinthe form of fumes,thatis,removingthe article from themlution having an attraction for'the solvent into the air does riot check evaporation of the solvent.

In the present'proces the ballsafter being submerged in the solution having an attraction for the solvent, are removed into a zone where the gaseous medium surrounding the article is saturated with fumes from the solvent. The resultofthisisanimmediatecheckof the evaporation of the fumes. While the evaporation is thus checked, the osmotic pressure throughout the coatingisequalized, so that the osmotic pressuregradientilattenslntoastralghtandflat After the osmotic Pressure within the coating hasbeen equalized or substantiallyso, the balls may be removed into the open air-where the vapor pressure is considerably lower, at which time evaporation may take place; but at the same time oxidation or a setting of the nitrocellulose coating takesplace. From this position the balls maybeadvancedintofumesagaintocheckthe Y evaporation, again permitting the osmotic pressure to be equalised throughout the coating.

' From the fumes the balls may be advanced back into the solution having an. attraction. for the solvent, beginning with the second cycle, whl cycle is the same as the former. When the ar- -not iniure the'coating, as theooating has set suiiiaciently so as to be immune from deleterimis eifects caused by'condensation.

forthebuiilngoperationlfthisis able pulley l4 driven by a belt I C actuated by a remove deposits formed while dousing the balls in the solution.

In order to carry out the process of coating articles with nitrocellulose material it is desirable to have suitable apparatus. For the purpose of illustration, the following apparatus will be described, although it is fully understood that various types of devices may be used for carrying out the process.

Referring to the drawing a cabinet II that is enclosed and preferably air-tight is provided with a rotary support i 2 for the article, which support may carry the article in any suitable manner. The support l2 may be Journalled in the ends of the cabinet Ill and provided with a shaft projecting through one end carrying a suitport l2 rotates, the article designated by the reference character 24. carried upon a suitable arm 26 fixedly attached to the support l2 rotates through a circular path." When the article 24 is below the liquid level 28 it is submerged in a solution that has an attraction for the solvent used in dissolving the nitrocellulose material used in coating the article 24. Y

The cabinet Ill being air-tight or practically so, will retain all fumes given off by the solvent of the coating. If acetone or Isotone is used, such acetone or Isotone as the. case may be, evaporates very rapidly both from the surface of the article 24 and from the surface of the solution 28. In so doing the fumes from the solvent are collected above the solution 28. The height thereof depends entirely upon the length of time the device has been in operation and the amount of air that may be added from time to time in exchange for fumes, as will appear more fully later. As the fumes given off by the solvent are heavier than air, the fumes will be confined to a fairly. well defined zone. Due to the slow rotation of the support l2, the fumes and the air are not intermixed to a great extent by the agitation caused by the rotation of the support If and the articles carried thereby.

It is desirable that a portion of the path of rotation of-the' article 24 extends through a'zone of air.

In so doing it seems that the nitrocellue lose material sets or cures-probably by oxidation. Therefore, it is desirable to maintain the zone of the fumes below the upper level of the path of the articles to be coated. Consequently the cabinet contains three zones, the one below the liquid level 28, the second a zone of fumes above the liquid level 2!, but below the air level 30. Above the fume zone is found air. It is not necessary that the two upper zones be well defined, providing there are sumcient fumes to create a saturated condition for a portion of the path, sufllcient to stop evaporation of thesolvent immediateiyupon the article leaving the solution, thereby permitting the osmotic pressure to seek its own level throughout the coating of the article. As the article'is advanced upwardly there may be a layer containing both air and,

' located in the opposite ends, instead of the use of vacuum devlca.

In loading the cabinets lid 32 maybe raised into dot-dash position, at which time the attendant may remove the coated articles that have been cured and substitute newly coated articles therefor. Due to the slow rotation of the support l2, this may be done while the machine rotates. The amount of fumes lost to the air seems to have no deleterious eifectin so doing, as the freshly coated articles generate additional fumes very rapidly.

As already referred to, the fresh coating has a great afilnity for moisture. It seems that by the present process condensation in the air in the upper portion of the cabinet Ill seems to have no deleterious effect upon the coating. It is believed that the fumes oi the solvent have sufiicient aflinity for the moisture in the air, so as to dehydrate the'air in the cabinet. This, however, is not definitely known at the present time. Sufllce to state that no deleterious effect by moisture accumulating upon the articles has been discovered while curing the coating in the I present apparatus.

The vat containing'the solution 28 may be provided with a suitable drain accessible from the exterior of the cabinet, so as .to withdraw the solution which has to be periodically replaced by new solution, as therelis a tendency for the solution to become saturated with the solvent if it is not replenished periodically. Such a drain has been shown schematically at 34. Likewise, an intake opening 36 for adding additional solution has been shown.

If it is desirable to ornament the finish, this may bedone by embossing the finish when it is partially dried or cured. For example, to provide a checkered finish a piece of cheese cloth or any other suitable woven fabric may be pressed against the partially set coating so as to produce the desired checkered eil'ect. Any other suitable design may be embossed by placing the article having the partially set coating in suitable embossingdies, which will leave the surface with a I and then apply -a second thin coating, which softens the outer surface of the first coating, emboss the article in this stage.

Defective coatings may be refinished by dipand ping the coated article into a second solution'that is very thin, having a large percentage of solvent,

- which solvent will dissolve the outer surface of the the first coating, causing it to smooth and elim'. inate pin holes and other defects therein.

Instead of dipping the coated article into a solution having a great attraction for the solvent used in dissolving the nitrocellulose material, the freshly coated articles may be sprayed by a spray formed from a solution forming fumes having an attraction for the solvent. A gasoline spray, for

couple, has beenfound to give excellent l ny other suitable spray may be used.

, This has been found to give excellent results andseerns to rapidly cure the coating. The spray is applied over a short period of time, after which the article is permitted to remain in a gaseous medium having an extremely high vapor presnu-e. so that the withdrawal 01' the solvent is checked while the article'is exposed to oxygen, which dries the nitrocellulose material, causing it to shrink, thereby increasing thepressure upon the solvent remaining in the coating. A second spraying may then take place so as to withdraw further solvent and the succeeding steps following the firstsprayiug being then repeated, sons to further cure the coating of the article.

Referring to the disclosure shown in Fig. 4, a portion of a ball 24 has been shown in section to show the details oi the finishing of the ball.

A small tubular sleeve 42 is inserted over the supporting stud I. This sleeve is preferably a preformed sleeve, having a solvent common to the nitrocellulose material inserted into the hole 44 in the core 46.- As the ball is coated with the nitrocellulose coating ll, a'homogeneous union is formed. In the absence of such a sleeve surrounding the stud, the mating 48 is usually defecrnains in the aperture .44 inv the core 46. A

threaded plug'il, having a solvent common to the sleeve, preferably a contrasting color, is then inserted in the aperture vacated by the stud 26.

After the ball 24 has been coated and the'plug II inserted the end of the plug 50 and the end of the sleeve 42 together with the adjacent coating 4| are then burnished to present'a uniform sur- Instead, of having the sleeve 42 and the plug 50 exposed at their outer ends, these may terminate within the outer surface of the coating 4' to perrnit the application of coating material outside of the ends of members 42 and 5! so as to produce a finished ball of a uniform color throughout;

'Theplugil as showr isthreaded. The threads may be omitted and the outer. surface softened by the solvent for the. nitrocellulose material which results in a homogeneous union between theplug I and the sleeve 42. Even though the plug I is threaded such a homogeneous union Althoughthe preferred modification of the devicehasbeendescrlbeditwlllbeunderstood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, which, gener-- ally stated consist in a device capable of carrying '7 out the objects set forth, in the novel parts, combination of parts and mode of operation, as disclosed anddellned in the appended claims.

Having thus described my invention, I claim: 1. The method of curing a nitrocellulose .coat-' ing-applied by dipping an article'in a nitrocellulme solution including the steps of rotating the article through a circular-path divided into three 'mneathe bottomsoneeontainingasolution hav-.

inganattractionforthesolventusedindisolvmaterial being practically insoluble'in sa'id solution, the'zone above the solution having a medium saturated with the fumesof the solvent and an air zone above the fume zone, the article being moved by cyclic rotation through the solution having an attraction for the solvent; into the fume 'zone; and then into the air zone so as to periodically subject the coating on the article to the eifects of the fluids of the several zones' 1 a 2. The method of coating articles with nitrocellulose material dissolved in asolvent including sixty percent acetone, twenty -flve percent isopropyl acetate and flfteenpercent anhydrous isopropanol, including the steps of applying the nitrocellulose material to the article to be coated and treating the coating in cycles, each, cycle including the rapid withdrawal of the solvent for a short period oftime by dipping the coated article into gasoline, followed by the surrounding of v v the article-by air having fumes of the solvent, so as to cause the nitrocellulose material to shrink.

3. The method ofcoating articles with nitrocellulose material dissolved in a solvent, including the steps of applying the nitrocellulose material to the article to be coated and treating the coating in aseries of cycles, each cycle including the rapid withdrawal of the solvent fora short period of time-by subjecting the coating to the influence of a medium havingattraction for the solvent used in dissolving the nitrocellulose material, in which mediumthe nitrocellulose material is substantially insoluble, followed by the surrounding of the article by avapor having high vapor pressure by having fumes of the solvent therein so as to causethe nitrocellulose material to-shrink. I V

4. The method of coating articles with nitrocellulose material dissolved in asolvent, including the steps of applying the coating to the article, I

subjecting the article to a fluid medium which rapidly withdraws a portion of the solvent, said medium having-attraction for the solvent used in dissolving the nitrocellulose material, in which medium the nitrocellulose material is substantially insoluble, followed by subjecting the article to a second medium practically saturated with the solvent to stop the withdrawal of the solvent,

which causes a shrinking of the coating so as to increase the pressure upon the solvent within the article and again rapidly withdrawing another portion of the solvent by again subjecting the coating to the influence of sald'fluid medium.

5. The method of coating an article with nitroY- v cellulose material dissolved in a solvent, including the steps of applying the nitrocellulose material to the article, subjecting the outer surface of the nitrocellulose material to the influenceof a solution having a great attraction for the solvent, the

- nitrocellulose material being practically insoluble in said solution, subjecting the article to'a medium substantially saturated-with the solvent, and subjecting the article to air so as to cause the nitrocellulose material to shrink to thereby increase the pressure upon the solvent within the article. 6. The method of coating an article with cellulose material disolved in a solvent, including-the steps of applying the cellulose material to the article, the article in a solution having a great attraction for the solvent, the cellulosematerial being practically insoluble in. said solutiol'i, changing the solution in contact with the I articleby a relative movement of one with respecttotheothensubjectingthesurtaceofthe u to a mediunrlnving ahigh vaporpressure article so as to increase the pressure upon the remaining solvent in the coating.-

7. The method of coating an article with nitrocellulose material dissolved in a solvent, including the steps of applying the nitrocellulose material to the article, spraying a solution having a great attraction for the solvent upon the coating of the article, the nitrocellulose material being practically insoluble in said solution, subjecting the surface of the article to a comparatively high vapor pressure of the solvent so as to deter the evaporation of the solvent in the coating so as to cause the coating to shrink to increase the pressure upon the remaining solvent.

8. A process of coating an article with nitrocellulose including the steps of dissolving the nitrocellulose in a solvent, dipping the article to be coated in the nitrocellulose solution, periodically moving the article into a solution having an attraction for the solvent in which the nitrocellulose is practically insoluble, transferring the article from the solution to a zone containing fumes of the solvent, transferring the article to a third zone where the article is subjected to air, returning the article to the fume zone to complete the article into a zone containing fumes of the solvent.

10. The method of coating an article with nitrocellulose including the steps of applying nitrocellulose dissolved in a solution by a solvent, placing the coated article in a solution having an attraction for the solvent, said nitrocellulose being practically insoluble in said solution, and removing the coated article into a gaseous medium including fumes from the solvent so as to allow the solvent remaining inv the coating to be substantially uniformly distributed therein.

11. The method of coating an article with nitrocellulose including the steps of applying a nitrocellulose coating to the article from nitrocellulose that has been: dissolved in a suitable solvent, subjecting the coating to a fluid solvent mixture medium having attraction for said-solvent. said medium substantially iafling to penstrate the nitrocellulose coating, to remove a portion of the solvent from the outer surface of coating to an article including the steps of dip ping the article in a nitrocellulose solution having a solvent for the nitrocellulose, periodically subjecting the coating to a fluid solvent mixture medium having attraction for said solvent, said medium substantially failing to penetrate the nitrocellulose coating to remove the solvent from the outer surface of the coating, subsequently redistributing the remaining solvent uniformly throughout the coating, subjecting the coated article to the influence of atmosphere and repeatingthe cycle until the coating has set sufficiently to dry under normal atmospheric conditions.

13. The method of curing a collodion coating including the steps of contacting the article with a fluid solvent mixture mediumhaving attraction for the solvent of the collodion coating, in which medium the collodion coating is substantially insoluble, to rapidly withdraw the'solvent for a short period of time and subsequently subjecting the coatedarticle to a medium having tion for the solvent of the collodion coating, in

which medium the collodion coating is substanti'ally insoluble, to rapidly withdraw the solvent for a short period of time, subsequently subjecting the coated article to a medium having sufficient fumes of the solvent therein to deterthe evaporation of the solvent, so as to reduce the volume of the coating thereby increasing the density of the solvent.

15; The method of cyclically curing a collodion coating, each cycle including the steps of contacting the article with a fluid solvent mixture medium having attraction for the solvent of the collodion coating, in which medium the collodion coating is substantially insoluble, to rapidly withdraw 'the solvent for a short period of time, and

subsequently subjecting the coated article to amedium having suflicient fumes of the solvent therein to deter the evaporation of the solvent, the cycles being repeated until the coating has cured suiiiciently to permit further curing thereof under normal atmospheric conditions.

16. The method of cyclically curing a-collodion coating, each cycle including the steps of contacting .the article with a fluid, solventmixture medium having attraction for the solvent of the collodion coating, in which medium the collodion coating is substantially insoluble, to rapidly withdraw thesolvent for a short period of time, subsequently subjecting the coated article to a medium having sufficient fumes therein to deter the evaporation of the solvent, so as to reduce the volume of the coating thereby increasing the density of the solvent, the cycles being repeated until the coating has cured sufllcientiy to permit further curing thereof under normal atmospheric conditions. I

17. The method of coating an article with a.

coating material dissolved in a solvent which is highly volatile at ordinary atmospheric temperatures, including the steps of applying the coating material to the article", subjecting the outer surface of the coating material to the influence of a solution having a great attraction for the solvent, the coating material being practically insoluble. in said solution, the solvent flowing from the coating material into the solution while in a liquid state at ordinary atmospheric temperatures; and subjecting the coated article ,to a medium substantially saturated with the solvent to arrest the rapid escape of the solvent from the coating material, said saturated medium having practically no effect upon the coating material per se.

1s. The method or coating articles with a coating material dissolved in a solvent which is highly volatile at ordinary atmospheric temperatures,

ames I coatingmaterlaldlasolvedbyaaolventwhlchia m m m m.

thesolventforaahortp a medium havlngsufllclent nm mm m mm m m m W a traction for the solvent of the coating, in which coating is substantially insoluble, pl'dly withdraw clewlth avapor saturated rlod of time, and tly. subjecting the m m J mm mm Mm.

each cycle Inthe solvent for 'hlghlyvolatlleatol dlnaryatmoephenctempenthe ccatlnz' turea, each cycle lncludin the steps of dipping having an attracthe coated article Into a solution having an atven vlngthe coatlnwhichmediumthecoatlngmr solution the lasuhstantlallyinaoluhle,tollowedbythe' tore o1 tmedlndiaaolvl'ng-eoated article to' to arrest the rapid fumes therein to eeoating material a ooatln: into a mm .m

lven

m mum art! the vent of o! by emu M m my? emmmwmmwmmmmm 

